Partitioned motor drive apparatus for subsea applications

Abstract

A system includes an above-surface control unit and a subsea motor drive unit. The above-surface control unit includes a variable speed motor control circuit configured to generate at least one switch control signal and a first communications circuit configured to transmit the at least one switch control signal over a communications medium. The subsea motor drive unit includes a driver circuit configured to be coupled to an electric motor and comprising at least one semiconductor switch and a second communications circuit coupled to the first communications circuit via the communications medium and configured to recover the transmitted at least one switch control signal and to apply the recovered at least one switch control signal to the driver circuit.

That which is claimed: 
     
         1 . A system comprising:
 a first communications circuit configured to transmit at least one switch control signal over a fiber optic cable; and   a motor drive unit positioned remotely with respect to first communications circuit, connected to the first communications circuit by the fiber optic cable and comprising:
 a driver circuit configured to be coupled to and drive an electric motor using at least one power semiconductor switch; and 
 a second communications circuit coupled to the first communications circuit via the fiber optic cable and configured to recover the transmitted at least one switch control signal and to apply the recovered at least one switch control signal to the at least one power semiconductor switch, 
   wherein the first communications circuit and the motor drive unit are powered by respective different power sources.